Nasalized form is sancire "make sacred, confirm, ratify, ordain." Sacred cow "object of Hindu veneration," is from 1891; figurative sense of "one who must not be criticized" is first recorded 1910, reflecting Western views of Hinduism. Sacred Heart "the heart of Jesus as an object of religious veneration" is from 1765.

jargon Reserved for exclusive use by something. The term might mean only writable by whatever it is sacred to. For example, "Register 7 is sacred to the interrupt handler" would mean that if any other code changed the contents of register 7, dire consequences would ensue. [Jargon File] (2002-12-30)